Golf products produced by a stoichiometrically imbalanced rim system

ABSTRACT

Disclosed herein are golf products, such as golf balls and/or components thereof, including the product of a fast-chemical-reaction mixture comprising a polyol and an isocyanate. The component is formed by reaction injection molding the reaction mixture. In the reaction mixture, the stoichiometry of the reactants is imbalanced.

CROSS REFERENCES TO RELATED APPLICATIONS

The present application is a continuation application of U.S. patentapplication Ser. No. 12/429,431, filed on Apr. 24, 2009, which is adivisional application of U.S. patent application Ser. No. 11/216,926,filed on Aug. 30, 2005, now U.S. Pat. No. 7,524,251.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not Applicable

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to golf equipment comprising afast-chemical-reaction-produced component. The component is made from areaction injection molding process in which the stoichiometry betweenreactants is imbalanced.

2. Description of the Related Art

Reaction injection molding (“RIM”) is a process used to make golfequipment or products such as golf balls and/or components thereof,including covers, cores, inner layers, etc. Highly reactive liquids areinjected into a closed mold, mixed usually by impingement and/ormechanical mixing in an in-line device such as a “peanut mixer”, andpolymerized primarily in the mold to form a coherent, one-piece moldedarticle. When used to make a polyurethane or polyurea article, RIMusually involves a rapid reaction between two types of reactants: (a) apolyol or other material with an active hydrogen, such as apolyfunctional alcohol or amine (hereinafter referred to as “polyol”);and (b) an isocyanate-containing compound (hereinafter referred to as“isocyanate”). The reactants are stored in separate tanks prior tomolding and may be first mixed in a mix-head upstream of a mold and theninjected into the mold. The liquid streams are metered in the desiredweight to weight ratio and fed into an impingement mix-head, with mixingoccurring under high pressure, e.g., 1500 to 3000 psi. The liquidstreams impinge upon each other in the mixing chamber of the mix-headand the mixture is injected into the mold. One of the liquid streamstypically contains a catalyst for the reaction. The reactants reactrapidly after mixing to gel and form polyurethane or polyurea polymers.Such mixtures, typically reacting in five minutes or less, are hereinreferred to as “fast-chemical-reaction” mixtures.

RIM offers several advantages over conventional injection andcompression molding techniques. For example, the reactants aresimultaneously mixed and injected into the mold, forming the desiredcomponent. In conventional techniques, the reactants must first be mixedin a mixer separate from the molding apparatus, and then added into theapparatus. In such a process, the mixed reactants first solidify andmust later be melted in order to properly mold the desired component.

Additionally, the RIM process requires lower temperatures and pressuresduring molding than injection or compression molding. Under the RIMprocess, the molding temperature is maintained from about 90 to about180° F., and usually at about 100-160° F., in order to ensure properinjection viscosity. Compression molding is typically completed at ahigher molding temperature of about 320° F. (160° C.). Injection moldingis completed at an even higher temperature range of 392-482° F.(200-250° C.). Molding at a lower temperature is beneficial when, forexample, the cover is molded over a very soft core so that the very softcore does not melt or decompose during the molding process.

Moreover, the RIM process creates more favorable durability propertiesin a golf ball component than conventional techniques. For example, agolf ball cover produced by a RIM process has a uniform or “seamless”cover in which the properties of the cover material in the region alongthe parting line are generally the same as the properties of the covermaterial at other locations on the cover, including at the poles. Theimprovement in durability is due to the fact that the reaction mixtureis distributed uniformly into a closed mold. This uniform distributionof the injected materials reduces or eliminates knit-lines and othermolding deficiencies which can be caused by temperature differencesand/or reaction differences in the injected materials. The RIM processresults in generally uniform molecular structure, density and stressdistribution as compared to conventional injection molding processes,where failure along the parting line or seam of the mold can occurbecause the interfacial region is intrinsically different from theremainder of the cover layer and, thus, can be weaker or more stressed.

Furthermore, the RIM process is relatively faster than conventionaltechniques. In the RIM process, the chemical reaction usually takesplace in under 5 minutes, typically in less than two minutes, sometimesin under one minute and, in many cases, in about 30 seconds or less. Thedemolding time may be 10 minutes or less. The molding process for theconventional methods itself typically takes about 15 minutes. Thus, theoverall speed of the RIM process makes it advantageous over theinjection and compression molding methods.

The term “demold time” generally refers to the mold release time, whichis the time span from the mixing of the components until the earliestpossible time at which the part may be removed from the mold. At thattime of removal, the part is said to exhibit sufficient “greenstrength.” The term “reaction time” generally refers to the setting timeor curing time, which is the time span from the beginning of mixinguntil the time at which the product no longer flows. Further descriptionof the terms setting time and mold release time are provided in the“Polyurethane Handbook,” edited by Gunter Oertel, Second Edition, ISBN1-56990-157-0, herein incorporated by reference.

Polyurethane and/or polyurea polymers are typically made from threereactants: alcohols, amines, and isocyanate-containing compounds. Bothalcohols and amines have a reactive hydrogen atom and are generallyreferred to as “polyols”. They react with the isocyanate-containingcompound, which is generally referred to as an “isocyanate.”

Several chemical reactions may occur during polymerization of isocyanateand polyol. Isocyanate groups (—N═C═O) that react with alcohols form apolyurethane, whereas isocyanate groups that react with an amine groupform a polyurea. A polyurethane itself may react with an isocyanate toform an allophanate and a polyurea can react with an isocyanate to forma biuret. Because the biuret and allophanate reactions occur on analready-substituted nitrogen atom of the polyurethane or polyurea, thesereactions increase cross-linking within the polymer. The stoichiometryof a polyurethane reaction is usually defined as the number ofequivalents of active hydrogen groups divided by the number ofequivalents of isocyanate groups multiplied by 100. In shorthand, theformula is [—OH or NH2]/[—NCO]*100. Typical systems utilize astoichiometry of 95 to 105. A stoichiometry of 95 represents a 5% excessof isocyanate, which ensures that all of the polyol, or soft component,is reacted, providing a fully cured material. A stoichiometry of 105 maybe used to obtain a slightly softer material, with the excess polyolacting as a plasticizer. A stoichiometry of 95 to 105 shall beconsidered balanced. An imbalanced stoichiometry shall be considered tobe less than 95 or greater than 105.

BRIEF SUMMARY OF THE INVENTION

Disclosed herein are various types of golf products or equipment,including golf balls and components thereof, and methods of making thesame. The components are made by reaction injection molding (RIM). Thecomponents include the product of a fast-chemical-reaction mixturecomprising an isocyanate and a polyol wherein the stoichiometry betweenthe reactants is imbalanced. Excess isocyanate is provided in the RIMprocess system and the imbalance is measured by the stoichiometry, withlower stoichiometry corresponding to excess isocyanate. In embodiments,the stoichiometry of the reaction is from about 50 to about 90. Infurther embodiments, the stoichiometry of the reaction is from about 60to about 90, and in more specific embodiments the stoichiometry of thereaction is from about 70 to about 85.

In one exemplary embodiment, a golf ball component, such as a cover, isprovided. The golf ball cover includes the product of afast-chemical-reaction mixture comprising an isocyanate and a polyolwherein the stoichiometry between the reactants is imbalanced.Additional golf ball components, such as a core or an intermediate layerproduced by these materials and processes are also disclosed herein.

In another exemplary embodiment, the golf ball component has a Shore Bhardness of 50 or more, including 75 or more. In one embodiment, thegolf ball component has a Shore B hardness of from about 80 to about 95.

In an additional exemplary embodiment, the golf ball component is a golfball cover having a Shore B hardness of 80 or more and exceptional shearresistance of 3.5 or less. The component may have a thickness of 0.0005inches to 0.200 inches,

In another embodiment, a method is provided for making a golf productthrough a RIM process wherein the stoichiometry between the reactants isimbalanced. A mixture comprising an isocyanate and a polyol is made,wherein the stoichiometry between the reactants is imbalanced. Themixture is then molded to form a golf product or component thereof.

Having briefly described the present invention, the above and furtherobjects, features and advantages thereof will be recognized by thoseskilled in the pertinent art from the following detailed description ofthe invention when taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 shows a cross-sectional view of a golf ball having a golf ballcover formed according to the present disclosure.

FIG. 2 shows a cross-sectional view of a golf ball having one or moregolf ball components according to the present disclosure.

FIG. 3 shows another cross-sectional view of a golf ball having one ormore golf ball components formed according to a reaction injectionmolding (RIM) process disclosed herein.

FIG. 4 is a process flow diagram which schematically depicts a reactioninjection molding process according to the present disclosure.

FIG. 5 shows a mold for reaction injection molding a golf ball cover asset forth herein.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to the drawings, FIG. 1 shows a golf ball having a covercomprising RIM polyurethane. The golf ball 10 includes a polybutadienecore 12 and a polyurethane cover 14 formed by RIM. The cover 14 is theproduct of a reaction mixture comprising an isocyanate and a polyolwherein the stoichiometry between the reactants is imbalanced.

FIG. 2 shows a golf ball having a core comprising RIM polyurethane. Thegolf ball 20 has a RIM polyurethane core 22 and a RIM polyurethane cover24. One or more of the components are formed from a reaction mixturecomprising an isocyanate and a polyol wherein the stoichiometry betweenthe reactants is imbalanced.

FIG. 3 shows a multi-layer golf ball 30 with a solid core 32 containingRIM polyurethane, a mantle or inner cover layer 34 comprising RIMpolyurethane, and an outer cover layer 36. The outer cover layer 36 canalso comprise RIM polyurethane. Alternatively, the inner cover layer 34and/or the outer cover layer 36 can comprise ionomer or anotherconventional golf ball cover material. Such conventional golf ball covermaterials typically contain titanium dioxide utilized to make the coverwhite in appearance.

The balls shown in FIG. 1 through FIG. 3 may be of a standard, enlargedor reduced size. Further, the core, intermediate and cover componentsmay comprise any number of layers or sub-parts desired.

FIG. 4 shows a process flow diagram for forming a RIM cover ofpolyurethane. Isocyanate from bulk storage is fed through line 80 to anisocyanate tank 100. The isocyanate is heated to the desiredtemperature, e.g. about 90 to about 150° F., by circulating it throughheat exchanger 82 via lines 84 and 86. The isocyanate can be carried ina solvent. Examples of suitable solvents include methyl isobutyl ketone,methyl amyl ketone, butyl acetate and propylene glycol monomethyl etheracetate. The use of methyl isobutyl ketone as the solvent orpart-solvent is advantageous because it tends to alleviate any potentialmoisture problems encountered with the acetate solvents.

The polyol is conveyed from bulk storage to a polyol tank 108 via line88. The polyol component may also contains additives, such asstabilizers, surfactants, flow modifiers, catalysts, combustionmodifiers, blowing agents, fillers, pigments, optical brighteners, andrelease agents to modify the physical characteristics of the product.The polyol is heated to the desired temperature, e.g. about 90 to about150° F., by circulating it through heat exchanger 90 via lines 92 and94. Dry nitrogen gas is fed from nitrogen tank 96 to isocyanate tank 100via line 97 and to polyol tank 108 via line 98. Isocyanate is fed fromisocyanate tank 100 via line 102 through a metering cylinder or meteringpump 104 into recirculation mix head inlet line 106. Polyol is fed frompolyol tank 108 via line 110 through a metering cylinder or meteringpump 112 into a recirculation mix head inlet line 114. The recirculationmix head 116 receives isocyanate and polyol, mixes them, and providesfor them to be fed through nozzle 118 into injection mold 120. Theinjection mold 120 has a top mold 122 and a bottom mold 124. Moldheating or cooling can be performed through lines 126 in the top mold122 and lines 140 in the bottom mold 124. The materials are kept undercontrolled temperature conditions to insure that the desired reactionprofile is maintained.

Inside the mix head 116, injector nozzles impinge the isocyanate andpolyol at ultra-high velocity to provide excellent mixing. Additionalmixing preferably is conducted using an aftermixer 130, which typicallyis constructed inside the mold between the mix head and the mold cavity.The reaction mixture viscosity should be sufficiently low to ensure thatthe empty space in the mold is completely filled. The reactant materialsgenerally are preheated to from about 80 to about 200° F. before theyare mixed. In most cases it is necessary to preheat the mold to, e.g.,from about 100 to about 180° F., to ensure proper injection viscosity.

FIG. 5 shows a mold used to make a golf ball cover. The mold includes agolf ball cavity chamber 134 in which a spherical golf ball cavity 132with a dimpled, inner spherical surface 136 is defined. The aftermixer130 can be a peanut aftermixer, as is shown in FIG. 5, or in some casesanother suitable type, such as a heart, harp or dipper. However, theaftermixer does not have to be incorporated into the mold design. Anoverflow channel 138 receives overflow material from the golf ballcavity 132 through a shallow vent 142. Heating/cooling passages 126 and140, which preferably are in a parallel flow arrangement, carry heattransfer fluids such as water, oil, etc. through the top mold 122 andthe bottom mold 124. Alternatively, the heating/cooling passages may bepresent in the platens of the press in which the mold is installed. Themold cavity contains retractable pins and is generally constructed inthe same manner as a mold cavity used to injection mold a thermoplasticgolf ball cover. However, two differences when RIM is used are thattighter pin tolerances generally are required, and a lower injectionpressure is used. Also, because of the lower injection pressure, themolds can be produced from lower strength material such as aluminum.Alternatively, the mold cavity may contain protrusions, or deep dimples,which support the insert during the injection process. This type of moldconstruction eliminates moving parts in the mold, facilitatingprocessing, and improving centering.

In the process depicted in FIG. 4, excess isocyanate is provided and thestoichiometry of the reaction is from about 50 to about 90. In furtherembodiments, the stoichiometry of the reaction is from about 60 to about90, and in more specific embodiments the stoichiometry of the reactionis from about 70 to about 85.

The variation in stoichiometry allows the use of one RIM machine to makegolf balls with different cover hardnesses. Under normal circumstances,very low stoichiometries, defined here as stoichiometries less than 90,typically result in brittle physical properties: lower elongation, lowertear strength, and lower abrasion resistance. This may be due toexcessive cross-linking. However, in a specific embodiment in thisdisclosure, a golf ball cover produced at low stoichiometry has produceda golf ball with higher hardness, and thus, reduced spin rates(favorable for increased distance) with no drop off in scuff or cutperformance or other physical properties. Without being limited to anyparticular theory, it may be hypothesized that the absence ofbrittleness in the preferred embodiments may be due to the specificchemical or kinetic mechanisms in the preferred polyurethane/polyureasystem (i.e. molecular chain length, polymerization kinetics, isocyanatecontent, etc.).

The reaction mixture comprises an isocyanate. The general structure ofan isocyanate is R—(NCO)_(n), where n is at least two, and R is anaromatic or an aliphatic group. The isocyanate may be also be aprepolymer. The prepolymer may be a blend of copolymers or a polymer.Furthermore, the prepolymer may comprise polyether, polyester, orpolybutadiene components. Aromatic isocyanates which may be used in thepresent disclosure include, but are not limited to, toluene diisocyanate(TDI); diphenyl-methane-diisocyanate (MDI); naphthalene-1,5-diisocyanate(NDI); m- and p-phenylene diisocyanate; toluene-2,4- and-2,6-diisocyanate; diphenylmethane-4,4′-diisocyanate;chlorophenylene-2,4-diisocyanate; naphthalene-1,5-diisocyanate;3-methyldiphenylmethane-4,4′-diisocyanate;4,4′-diisocyanate-3,3′-dimethyldiphenylmethane; diphenyl etherdiisocyanate; and 3-methyldiphenylmethane-4,4′-diisocyanate. Generally,aromatic isocyanates exhibit fast reaction times and good physicalproperties, but tend to have poor light fastness (i.e., discolorationdue to UV light).

Aliphatic isocyanates which may be used in the present disclosureinclude, but are not limited to, hexamethylene diisocyanate (HDI);isophorone diisocyanate (IPDI); tetramethylene diisocyanate;octamethylene diisocyanate; decamethylene diisocyanate; dodecamethylenediisocyanate; tetradecamethylene diisocyanate; derivatives of lysinediisocyanate; tetramethylxylylene diisocyanate; trimethylhexanediisocyanate or tetramethylhexane diisocyanate; cycloaliphaticdiisocyanates such as 1,4-, 1,3- or 1,2-diisocyanatocyclohexane;4,4-di(isocyanatocyclohexyl)methane;1-isocyanato-3,3,5-trimethyl-5-(isocyanatemethyl)-cyclohexane-(isophoronediisocyanate) or 2,4- or 2,6-diisocyanato-1-methylcyclohexane. Aliphaticisocyanates generally exhibit good light fastness and UV stability, butare slower to react and produce softer polymers than the aromaticisocyanates.

The reaction mixture also comprises a polyol, which can be selected froma polyalcohol, a polyamine, or a combination thereof. When the polyol isan alcohol, it is typically a polyfunctional alcohol, such as a diol,triol, etc., depending on the number of hydroxyl groups. Compoundscontaining the hydroxyl functional group can include polyesters,polyethers, and polybutadienes. Alternately, the hydroxyl functionalpolyol is ethylenically saturated. Some saturated polyethers includepolymers of propylene oxide or propylene oxide/ethylene oxide; suchmaterials are usually triols or diols. In specific embodiments, apolyether polyol or a polyester polyol is selected.

The alcohol may also be a glycol. Examples include, but are not limitedto, polyethylene glycol; polypropylene glycol (PPG); polybutyleneglycol; pentane glycol; hexane glycol; benzene glycol; xylene glycol;2,3-dimethyl-2,3-butane diol; dipropylene glycol; and their polymers.

A polyamine may also be used in the reaction mixture. Examples include,but are not limited to, diethyltoluenediamine,tetramethyl-ethylenediamine; dimethylbenzylamine; diethylbenzylamine;pentamethyldiethylenetriamine; dimethyl cyclohexylamine;tetramethyl-1,3-butanediamine; pentamethyldipropylenetriamine;1,2-dimethylimidazole; 2-methylimidazole; andbis-(dimethylaminoethyl)ether.

Other reactants containing a reactive hydrogen atom that would reactwith the isocyanate to form a polyurethane or polyurea polymer can beutilized. Such materials include polyamines, polyamides, short oilalkyds, castor oil, epoxy resins with secondary hydroxyl groups,phenolic resins, hydroxyl functional dendrimers, and hydroxyl functionalvinyl resins. Suitable examples of such materials include ANCAMINE 2071,a modified polyamine marketed by Pacific Anchor Chemical Corporation,Los Angeles, Calif.; EPON V-40, a polyamide marketed by Shell OilCompany, Houston, Tex.; AROPLAZ 1133-X-69, a short oil alkyd byReichhold Inc., Minneapolis, Minn.; EPON resin 828, an epoxy resinmarketed by Shell Oil Company; PENTALYN 802A, a phenolic modifiedpolyester resin marketed by Hercules Inc., Wilmington, Del.; and VAGH, ahydroxyl functional vinyl resin marketed by Union Carbide, Danbury,Conn. Non-limiting examples of other suitable RIM systems for use in, orin combination with, the present disclosure are VIBRARIM reactioninjection moldable polyurethane and polyurea systems from CromptonCorporation (Middlebury, Conn.), BAYFLEX elastomeric polyurethane RIMsystems, BAYDUR GS solid polyurethane RIM systems, PRISM solidpolyurethane RIM systems, all from Bayer Corp. (Pittsburgh, Pa.),SPECTRIM reaction moldable polyurethane and polyurea systems from DowChemical USA (Midland, Mich.), including SPECTRUM MM 373-A (isocyanate)and 373-B (polyol), and ELASTOLIT SR systems from BASF (Parsippany,N.J.). The golf ball components of the present disclosure may also beoptionally cross-linked by irradiation. Numerous ways are known toinduce cross-linking in a polymer by free radical initiation, includingperoxide initiation and UV irradiation. Other forms of particleirradiation, including electron beam, also can be used.

Gamma radiation allows golf balls to be irradiated in bulk. Gammaradiation penetrates relatively deep into the material undergoingirradiation, but also increases cross-linking of the inner core.Accordingly, the compression of the core can be adjusted to allow forthe increase in hardness stemming from the cross-linking. Electron beamtechniques are faster but cannot be used for treating in bulk as theelectron beam does not sufficiently penetrate into the material and theproduct typically needs to be rotated to obtain an even or uniformcross-link density. The type of irradiation to be used will depend inpart upon the underlying layers. For example, certain types ofirradiation may degrade windings in a wound golf ball. On the otherhand, balls with a solid core would not be subject to the same concerns.However, with any type of core, certain types of irradiation will tendto cross-link and thus harden the core. Depending upon whether this typeof effect is sought or is to be avoided, the appropriate type ofirradiation can be selected.

The level of radiation employed depends upon the desired endcharacteristics of the final golf ball component. However, generally awide range of dosage levels may be used. For example, total dosages ofup to about 12.5 or even 15 Mrads may be employed. Preferably, radiationdelivery levels are controlled so that the golf ball component is notheated above about 80° C. (176° C.) while being cross-linked.

Golf ball components may have indicia and/or logos stamped or formedthereon. Such indicia can be applied by printing using a material or asource of energetic particles after the ball core and/or cover have beenreaction-injection-molded according to the present invention. Printedindicia can be formed from materials known in the art, such as ink, foil(for use in foil transfer), etc. Indicia printed using a source ofenergetic particles or radiation can be applied by burning with a laser,burning with heat, directed electrons, or light, phototransformationsof, e.g., U.V. ink, impingement by particles, impingement byelectromagnetic radiation, etc. Furthermore, the indicia can be appliedin the same manner as an in-mold coating, i.e., by applying the indiciato the surface of the mold prior to molding of the cover.

The resulting golf ball component comprises from about 5 to about 100weight percent of polyurethane/polyurea based on the weight of the golfball component. The product of the fast-chemical-reaction mixture mayalso comprise other agents. When the golf ball component is an outercover layer, pigments or dyes, accelerators and UV stabilizers can beadded. An example of a suitable white pigment is titanium dioxide.Examples of suitable UV light stabilizers are provided in commonlyassigned U.S. Pat. No. 5,494,291, herein totally incorporated byreference. Furthermore, compatible polymeric materials can be added. Forexample, when the component comprises polyurethane and/or polyurea, suchpolymeric materials include polyurethane ionomers, polyamides, etc.Fillers can also be incorporated into the golf ball component, includingthose listed below.

Golf balls comprising a golf ball component according to the presentdisclosure are also contemplated. If the component is a cover layer,then a wide array of materials may be used for the cores and mantlelayer(s) of the golf ball. For instance, the core and mantle or interiorlayer materials disclosed in U.S. Pat. Nos. 5,833,553, 5,830,087,5,820,489 and 5,820,488, all of which are hereby incorporated byreference in their entirety, may be employed. If the component is a coreor inner layer, then a variety of conventional materials may be used forone or more cover layers. For instance, the cover layer(s) may employmaterials such as disclosed in U.S. Pat. Nos. 6,309,314, 6,277,921,6,220,972, 6,150,470, 6,126,559, 6,117,025, 5,902,855, 5,895,105,5,688,869, 5,591,803, and 5,542,677, all of which are herebyincorporated by reference in their entireties.

If the component is a golf ball cover, the golf ball may be a two-pieceor multi-layer ball having a wound core, a solid, non-wound core, aliquid core, or a gel core.

One or more intermediate or cover layers can be included havingdifferent characteristics. It is particularly advantageous to have anouter cover Shore B hardness of 50 or more, including 70 or more. Thesemeasurements are made in general accordance with ASTM 2240, except theyare made on the ball itself and not on a plaque. The outer layer is fromabout 0.005 to about 0.20 inches in thickness, including about 0.001 toabout 0.100 inches in thickness. Thickness is defined as the averagethickness of the non-dimpled cover of the outer cover. The outer coveris comprised of a relatively soft, low flex modulus (about 1000 psi orgreater, including from about 2000 psi to about 50000 psi) material asnoted above. The cover exhibits good durability characteristics (i.e.,groove shear resistance of 3.5 or less, on a scale of 1 to 6 (lowernumbers are better) corresponding to no loss or significant fraying ofthe cover material, and cut resistance of 3 or less on a scale of 1 to 5(lower numbers are better) corresponding to a slight dent in the covernot discernible by touch). The groove shear resistance is measured ongolf balls struck by a 56 degree wedge clubhead at about 103 feet persecond. The cut resistance is measured on golf balls subjected to anoff-center blow by a blade with an approximate 5/64″ radius attached toa sled weighing approximately 6 lbs dropped from a height of about 42inches.

The outer cover layer formed from the fast-chemical-reaction product ofan isocyanate and a polyol wherein the stoichiometry between thereactants is imbalanced, when molded over the core (and inner cover orlayer, or layers if a multi-layer cover) results in a golf ball having acoefficient of restitution (“COR”) of at least 0.760, including at least0.800. The COR of the ball will depend upon the properties of both thecore and the cover and/or intermediate layer(s).

When utilizing an outer cover layer formed from the reaction product ofan isocyanate and a polyol wherein the stoichiometry between thereactants is imbalanced, a conventional core component can be utilized.The core of the golf ball can be formed of a solid, or an encapsulatedsphere filled with a gas, a liquid or a gel, or any other substance thatwill result in a core or an inner ball (core and a at least one innercover layer, if the ball is a multi-layer ball), having the desired COR,compression and hardness and other physical properties.

The cores of the golf ball typically have a coefficient of restitutionof about 0.750 or more, more preferably 0.770 or more, and a PGAcompression of about 90 or less, and more preferably 70 or less.Furthermore, in some applications it may be desirable to provide a corewith a coefficient of restitution of about 0.780 to about 0.790 or more.The core used in the golf ball is preferably a solid, but any core typeknown in the art may be used, such as wound, liquid, hollow, metal, andthe like. The term “solid cores” as used herein refers not only to onepiece cores but also to those cores having a separate solid layerbeneath the covers and over the central core. The cores generally have aweight of about 25 to about 40 grams and preferably about 30 to about 40grams. Larger and heavier cores, or lighter and smaller cores, may alsobe used when there is no desire to meet U.S.G.A. or R. & A. standards.

When the golf ball of the present disclosure has a solid core, this corecan be compression molded from a slug of uncured or lightly curedelastomer composition comprising a high cis content polybutadiene and ametal salt of an α, β, ethylenically unsaturated carboxylic acid such aszinc mono- or diacrylate or methacrylate. To achieve higher coefficientsof restitution and/or to increase hardness in the core, the manufacturermay include a small amount of a metal oxide such as zinc oxide. Inaddition, larger amounts of metal oxide than are needed to achieve thedesired coefficient may be included in order to increase the core weightso that the finished ball more closely approaches the U.S.G.A. upperweight limit of 1.620 ounces.

Non-limiting examples of other materials that may be used in the corecomposition include, but are not limited to, compatible rubbers orionomers, and low molecular weight fatty acids such as stearic acid.Free radical initiator catalysts such as peroxides may be admixed withthe core composition so that on the application of heat and pressure, acuring or cross-linking reaction takes place. The core may also beformed from any other process for molding golf ball cores known in theart.

A thread wound core may comprise a liquid, solid, gel or multi-piececenter. The thread wound core is typically obtained by winding a threadof natural or synthetic rubber, or thermoplastic or thermosettingelastomer such as polyurethane, polyester, polyamide, etc., on a solid,liquid, gel or gas filled center to form a thread rubber layer that isthen covered with one or more mantle or cover layers. Additionally,prior to applying the cover layer(s), the thread wound core may befurther treated or coated with an adhesive layer, protective layer, orany substance that may improve the integrity of the wound core duringapplication of the cover layers and ultimately in usage as a golf ball.

The core, preferably a solid core, is about 1.2 to about 1.6 inches indiameter, although it may be possible to use cores in the range of about1.0 to about 2.0 inches. If the ball has a single cover layer, the coresize may be up to about 1.660 inches.

The present disclosure includes one or more auxiliary layers disposed onthe core, and a preferably immediately adjacent to the outer coresurface. For example, for some applications, it may be preferred todeposit a barrier coating that limits transmission of moisture to thecore. Such barrier coatings or layers are relatively thin. Generally,such coatings are at least 0.0001 inch, and preferably, at least 0.003inch in thickness. Furthermore an adhesion promoting layer may be usedbetween the cover layers and/or the core, or the cover and core having abarrier coating disposed thereon. Such adhesion promoting layers areknown in the art and may be used in combination with the featuresdescribed herein. See for example U.S. Pat. No. 5,820,488, which ishereby incorporated by reference.

The inner cover layer that is molded over the core is preferably about0.0005 inch to about 0.15 inch in thickness. The inner ball thatincludes the core and inner cover layer(s), or core for a two pieceball, preferably has a diameter in the range of 1.25 to 1.67 inches. Theouter cover layer is about 0.0005 inch to about 0.20 inch thick.Together, the core, the inner cover layer(s) and the outer cover layer(or core and single cover layer) combine to form a ball having adiameter of 1.680 inches or more, the minimum diameter permitted by therules of the U.S.G.A. and weighing no more than 1.62 ounces. If desired,golf balls of different weights and diameters may also be formed if therules of the U.S.G.A. are not an issue.

In a particular embodiment of the disclosure, the golf ball has a dimplepattern that provides dimple coverage of 65% or more, preferably 75% ormore, and ore preferably about 80 to 85% or more In another embodiment,there are from 300 to less than 500 dimples, preferably from about 340to about 440 dimples.

Specifically, the arrangement and total number of dimples are notcritical and may be properly selected within ranges that are well known.For example, the dimple arrangement may be an octahedral, dodecahedralor icosahedral arrangement. The total number of dimples is generallyfrom about 250 to about 600, and especially from about 300 to about 500.The golf balls of the present invention may comprise circular ornon-circular dimples or any combination.

In a further embodiment, the golf ball typically is coated with adurable, abrasion-resistant, relatively non-yellowing finish coat orcoats if necessary. The finish coat or coats may have some opticalbrightener and/or pigment added to improve the brightness of thefinished golf ball.

In one embodiment, from 0.001 to about 10% optical brightener may beadded to one or more of the finish coatings. If desired, opticalbrightener may also be added to the cover materials. One type ofpreferred finish coatings are solvent based urethane coatings known inthe art. It is also contemplated to provide a transparent outer coatingor layer on the final finished golf ball.

Golf balls also typically include logos and other markings printed ontothe dimpled spherical surface of the ball. Paint, typically clear paint,is applied for the purposes of protecting the cover and improving theouter appearance before the ball is completed as a commercial product.

If the core in the component is the product of a reaction mixture of anisocyanate and a polyol wherein the stoichiometry between the reactantsis imbalanced, the same processing conditions are used as are describedabove with respect to covers. One difference is, of course, that noretractor pins are needed in the mold. Furthermore, an undimpled,smaller mold is used. If, however, a one piece ball is desired, adimpled mold would be used.

If the component is a golf ball core layer, it typically contains 0 to20 weight percent of filler material, and in specific embodiments 1 to15 weight percent based on the weight of the layer.

If the component is an inner cover layer or mantle layer, it typicallycontains 0 to 60 weight percent of filler material; in other embodimentsit contains 1 to 30 weight percent or 1 to 20 weight percent fillermaterial based on the weight of the layer.

If the component is an outer cover layer, it typically contains 0 to 20weight percent of filler material in other embodiments it contains 1 to10 weight percent or 1 to 5 weight percent filler material based on theweight of the layer.

Fillers are used to adjust the density, flex modulus, mold release,and/or melt flow index of a layer. With some fillers, up to about 200parts by weight can be used. When the filler is for adjustment ofdensity or flex modulus of a layer, it is present in an amount of atleast 5 parts by weight based upon 100 parts by weight of the layer.

A density adjusting filler is used to control the moment of inertia, andthus the initial spin rate of the ball and spin decay. The addition inone or more layers, and particularly in the outer cover layer, of afiller with a lower specific gravity than the resin composition resultsin a decrease in moment of inertia and a higher initial spin rate thanwould result if no filler were used. The addition in one or more of thecover layers, and particularly in the outer cover layer, of a fillerwith a higher specific gravity than the resin composition, results in anincrease in moment of inertia and a lower initial spin rate. Highspecific gravity fillers are preferred as less volume is used to achievethe desired inner or outer cover total weight. Nonreinforcing fillersare also preferred as they have minimal effect on COR. Preferably, thefiller does not chemically react with the resin composition to asubstantial degree, although some reaction may occur when, for example,zinc oxide is used in a shell layer which contains some ionomer. Thefiller usually has a specific gravity which is at least 0.05, and inspecific embodiments at least 0.1, higher or lower than the specificgravity of the layer composition. In further embodiments, densityadjusting fillers are used which have specific gravities which arehigher or lower than the specific gravity of the resin composition by0.2 or more or by 2.0 or more.

A flex modulus adjusting filler is a filler which, e.g. when used in anamount of 1 to 100 parts by weight based upon 100 parts by weight ofresin composition, will raise or lower the flex modulus (ASTM® D-790) ofthe resin composition by at least 1% and preferably at least 5% ascompared to the flex modulus of the resin composition without theinclusion of the flex modulus adjusting filler.

A mold release adjusting filler is a filler which allows for the easierremoval of a part from a mold and eliminates or reduces the need forexternal release agents which otherwise could be applied to the mold. Amold release adjusting filler typically is used in an amount of up toabout 2 weight percent based upon the total weight of the layer.

A melt flow index adjusting filler is a filler which increases ordecreases the melt flow, or ease of processing, of the composition.

If the component is a layer, it may contain coupling agents thatincrease adhesion of materials within a particular layer, e.g. to couplea filler to a resin composition, or between adjacent layers.Non-limiting examples of coupling agents include titanates, zirconatesand silanes. Coupling agents typically are used in amounts of 0.1 to 2weight percent based upon the total weight of the composition in whichthe coupling agent is included.

Fillers which may be employed in layers other than the outer cover layermay be or are typically in a finely divided form, for example, in a sizegenerally less than about 20 mesh, preferably less than about 100 meshU.S. standard size, except for fibers and flock, which are generallyelongated. Flock and fiber sizes should be small enough to facilitateprocessing. Filler particle size will depend upon desired effect, cost,ease of addition, and dusting considerations. The filler preferably isselected from the group consisting of precipitated hydrated silica,clay, talc, asbestos, glass fibers, aramid fibers, mica, calciummetasilicate, barium sulfate, zinc sulfide, lithopone, silicates,silicon carbide, diatomaceous earth, polyvinyl chloride, carbonates,metals, metal alloys, tungsten carbide, metal oxides, metal stearates,particulate carbonaceous materials, micro balloons, and combinationsthereof.

Specific embodiments of the disclosure will now be described in detail.These examples are intended to be illustrative, and the disclosure isnot limited to the materials, conditions, or process parameters setforth in these embodiments. All parts and percentages are by weightunless otherwise indicated.

EXAMPLES

Three types of golf balls were made on the same machine with the samemantles and cores. The stoichiometries of the golf ball covers werevaried. The first comprised an 18.7% NCO prepolymer, unstabilized, at astoichiometry of 95 and a ratio (NCO:OH) of 87:100 by weight and wasdesignated as AdiRIM X021. The second comprised 16.58% NCO, at astoichiometry of 95 and a ratio of 98.6:100 and was designated asVibraRIM (95 ST). The third comprised 16.58% NCO, at a stoichiometry of80 and a ratio of 117.1:100 and was designated as VibraRIM (80 ST). TheAdiRIM system served as an example of a means of increasing the hardnessof a polymer through increasing the NCO content of the prepolymer. Thehigher NCO content of these prepolymers, at the same stoichiometry asthe VibraRIM (95 ST) example, were meant to yield a harder polymer. ThisAdiRIM example and the VibraRIM (95 ST) example served as controls.Several dozen balls were made of each type and tested for physicalproperties, durability, Shore B hardness, scuff resistance, cutresistance, weatherability, and total spin rate.

TABLE 1 summarizes the constructions and test results for the examplesof this disclosure. The physical properties of all three ball types arevery similar. Durability, weatherability, and paint adhesion (wetbarrel). Cut resistance and scuff resistance (both Paint Scuff andMaterial Scuff) were also comparable amongst the samples. The Shore Bmeasurements, taken by hand on golf balls, indicated slightly hardercovers on the AdiRIM component and the VibraRIM (80 ST) component.However, in the case of the VibraRIM (80 ST) sample, the spin rates onthe drivers and the 5-iron were lower than either of the controls, whilestill maintaining favorable spin rates on the pitching wedge and chipshots. Taken together, these examples indicate that a golf ballcomponent made at an imbalanced stoichiometry of 80, according to thepresent disclosure, shows comparable material toughness to those madewith balanced stoichiometries and produced golf balls with slightlyharder covers and thus, reduced spin rates.

TABLE ONE 1 Unstabilized Higher 2 3 NCO Prepolymer Standard PrepolymerStandard Prepolymer with Standard Polyol with Standard Polyol withStandard Polyol Ball Description @ .021″ and 95 stoich @ .021″ and 95stoich @ .021″ and 80 stoich Actual Size (in) 1.550 (0.0016) 1.550(0.0016) 1.550 (0.0016) Core Weight (g) 36.88 (0.12) 36.88 (0.12) 36.88(0.12) Instron 0.092 (0.0014) 0.092 (0.0014) 0.092 (0.0014) CoR 0.800(0.0024) 0.800 (0.0024) 0.800 (0.0024) Actual Size (in) 1.639 (.0007)1.639 (.0007) 1.639 (.0007) Mantle Weight (g) 42.45 (0.06) 42.45 (0.06)42.45 (0.06) Instron .087 (.0014) .087 (.0014) .087 (.0014) CoR .809(.0014) .809 (.0014) .809 (.0014) Actual Pole Size(in) 1.683 (.0010)1.683 (.0005) 1.683 (.0006) Ball Equator Size (in) 1.683 (.0008) 1.683(.0005) 1.683 (.0011) Weight (g) 45.49 (.05) 45.48 (.04) 45.42 (.05)Instron .086 (.0016) .087 (.0015) .087 (.0017) CoR .805 (.0026) .803(.0012) .805 (.0032) NezFactor 891 890 892 Total Spin (MEAN USGA Driver(deg, fps, RPM) 10.0, 260.0, 2603 10.1, 259.1, 2543 10.1, 259.5, 2406VALUES) Pro Driver (deg, fps, RPM)  9.6, 240.8, 3081  9.6, 240.4, 3118 9.6, 240.8, 3046 Am. Driver (deg, fps, RPM) 11.9, 201.8, 3463 11.9,201.7, 3549 12.0, 202.0, 3400 5-Iron (deg, fps, RPM) 14.0, 188.4, 630013.9, 188.3, 6439 14.2, 188.4, 6240 P. Wedge (deg, fps, RPM)  25.6,138.7, 10212  25.6, 138.7, 10213  25.7, 138.7, 10115 76 fps Chip (deg,fps, RPM) 28.8, 75.8, 7232 28.6, 76.1, 7375 28.8, 76.1, 7279 60 fps Chip(deg, fps, RPM) 25.6, 61.0, 5973 25.4, 60.9, 6051 25.7, 60.9, 5914Physical Paint Scuff 3.25 (paint only) 3.45 (paint only) 3.4 (paintonly) Testing Material Scuff    2.0    2.1    2.0 Cut 3 (mostly paint) 4(mostly paint) 4 (mostly paint) Shore B (Median values)  89  88  89 WetBarrel Pass Pass Pass Weatherometer Pass Pass Pass Cold Crack (6 ballseach to No Failures No Failures No Failures 5 blows) Barrel (18 ballseach to No Failures No Failures 1 @ 500 (1 cover failure 500 blows) alsonoted @ 500) High Speed (18 balls each 1 each @ 138, 154, 171, 1 each @103, 113, 1 each @ 97, 152, 153, to 200 blows) 189, and 190 137, 2@ 152,1@ 155, and 194 1@198

From the foregoing it is believed that those skilled in the pertinentart will recognize the meritorious advancement of this invention andwill readily understand that while the present invention has beendescribed in association with a preferred embodiment thereof, and otherembodiments illustrated in the accompanying drawings, numerous changes,modifications and substitutions of equivalents may be made thereinwithout departing from the spirit and scope of this invention which isintended to be unlimited by the foregoing except as may appear in thefollowing appended claims. Therefore, the embodiments of the inventionin which an exclusive property or privilege is claimed are defined inthe following appended claims.

1. A method for making a golf ball component, the method comprising:forming a fast-chemical-reaction mixture comprising an aliphaticisocyanate and a polyol, wherein the mixture has a stoichiometry of fromabout 50 to about 90 that is imbalanced and has a nitrogen-carbon-oxygengroup content of the mixture is greater than a hydroxyl content of themixture; and molding the reaction mixture to form a golf ball componentin a reaction time of two minutes or less.
 2. The method of claim 1wherein the mixture has a stoichiometry of from about 60 to about
 90. 3.The method of claim 2 wherein the mixture has a stoichiometry of fromabout 70 to about
 85. 4. The golf ball component produced by the methodof claim
 1. 5. The method of claim 1 wherein the component is selectedfrom the group consisting of a one-piece golf ball, a cover, anintermediate layer, a layer of a cover, a core, and a layer of a core.6. The method of claim 1 wherein the golf ball component has a Shore Bhardness of 50 or more.
 7. The method of claim 1 wherein the golf ballcomponent has a Shore B hardness of from about 80 to about
 95. 8. Themethod of claim 1 wherein the component is formed from thefast-chemical-reaction mixture in a reaction time of two minutes orless.